use actix_web::{HttpResponse, web};
use serde::{Deserialize, Serialize};

use shanty_db::entities::wanted_item::WantedStatus;
use shanty_db::queries;
use shanty_search::SearchProvider;
use shanty_tag::provider::MetadataProvider;

use crate::error::ApiError;
use crate::state::AppState;

#[derive(Deserialize)]
pub struct PaginationParams {
    #[serde(default = "default_limit")]
    limit: u64,
    #[serde(default)]
    offset: u64,
}
fn default_limit() -> u64 {
    50
}

#[derive(Deserialize)]
pub struct AddArtistRequest {
    name: Option<String>,
    mbid: Option<String>,
}

#[derive(Serialize)]
struct ArtistListItem {
    id: i32,
    name: String,
    musicbrainz_id: Option<String>,
    total_watched: usize,
    total_owned: usize,
    total_items: usize,
}

#[derive(Serialize, Deserialize, Clone)]
struct CachedAlbumTracks {
    release_mbid: String,
    tracks: Vec<CachedTrack>,
}

#[derive(Serialize, Deserialize, Clone)]
struct CachedTrack {
    recording_mbid: String,
    title: String,
}

#[derive(Serialize)]
struct FullAlbumInfo {
    mbid: String,
    title: String,
    release_type: Option<String>,
    date: Option<String>,
    track_count: u32,
    local_album_id: Option<i32>,
    watched_tracks: u32,
    owned_tracks: u32,
    downloaded_tracks: u32,
    total_local_tracks: u32,
    status: String,
}

pub fn configure(cfg: &mut web::ServiceConfig) {
    cfg.service(
        web::resource("/artists")
            .route(web::get().to(list_artists))
            .route(web::post().to(add_artist)),
    )
    .service(web::resource("/artists/{id}/full").route(web::get().to(get_artist_full)))
    .service(
        web::resource("/artists/{id}")
            .route(web::get().to(get_artist))
            .route(web::delete().to(delete_artist)),
    );
}

async fn list_artists(
    state: web::Data<AppState>,
    query: web::Query<PaginationParams>,
) -> Result<HttpResponse, ApiError> {
    let artists = queries::artists::list(state.db.conn(), query.limit, query.offset).await?;
    let wanted = queries::wanted::list(state.db.conn(), None).await?;

    let mut items: Vec<ArtistListItem> = Vec::new();
    for a in &artists {
        let artist_wanted: Vec<_> = wanted
            .iter()
            .filter(|w| w.artist_id == Some(a.id))
            .collect();

        // Check if we have cached artist-level totals from a prior detail page load
        let cache_key = format!("artist_totals:{}", a.id);
        let cached_totals: Option<(u32, u32, u32)> =
            if let Ok(Some(json)) = queries::cache::get(state.db.conn(), &cache_key).await {
                serde_json::from_str(&json).ok()
            } else {
                None
            };

        let (total_watched, total_owned, total_items) =
            if let Some((avail, watched, owned)) = cached_totals {
                (watched as usize, owned as usize, avail as usize)
            } else {
                // Fall back to wanted item counts
                let total_items = artist_wanted.len();
                let total_owned = artist_wanted
                    .iter()
                    .filter(|w| w.status == WantedStatus::Owned)
                    .count();
                (total_items, total_owned, total_items)
            };

        items.push(ArtistListItem {
            id: a.id,
            name: a.name.clone(),
            musicbrainz_id: a.musicbrainz_id.clone(),
            total_watched,
            total_owned,
            total_items,
        });
    }

    Ok(HttpResponse::Ok().json(items))
}

async fn get_artist(
    state: web::Data<AppState>,
    path: web::Path<String>,
) -> Result<HttpResponse, ApiError> {
    let id_or_mbid = path.into_inner();
    if let Ok(id) = id_or_mbid.parse::<i32>() {
        let artist = queries::artists::get_by_id(state.db.conn(), id).await?;
        let albums = queries::albums::get_by_artist(state.db.conn(), id).await?;
        Ok(HttpResponse::Ok().json(serde_json::json!({
            "artist": artist,
            "albums": albums,
        })))
    } else {
        Err(ApiError::BadRequest(
            "use /artists/{id}/full for MBID lookups".into(),
        ))
    }
}

/// Fetch (or retrieve from cache) the tracklist for a release group.
/// Cache key: `artist_rg_tracks:{release_group_id}`
async fn get_cached_album_tracks(
    state: &AppState,
    rg_id: &str,
    first_release_id: Option<&str>,
    ttl_seconds: i64,
    extend_ttl: bool,
) -> Result<CachedAlbumTracks, ApiError> {
    let cache_key = format!("artist_rg_tracks:{rg_id}");

    // Check cache first
    if let Some(json) = queries::cache::get(state.db.conn(), &cache_key)
        .await
        .map_err(|e| ApiError::Internal(e.to_string()))?
        && let Ok(cached) = serde_json::from_str::<CachedAlbumTracks>(&json)
    {
        // Extend TTL if artist is now watched (upgrades 7-day browse cache to permanent)
        if extend_ttl {
            let _ = queries::cache::set(
                state.db.conn(),
                &cache_key,
                "musicbrainz",
                &json,
                ttl_seconds,
            )
            .await;
        }
        return Ok(cached);
    }

    // Not cached — resolve release MBID and fetch tracks
    let release_mbid = if let Some(rid) = first_release_id {
        rid.to_string()
    } else {
        // Browse releases for this release group
        resolve_release_from_group(rg_id).await?
    };

    let mb_tracks = state
        .mb_client
        .get_release_tracks(&release_mbid)
        .await
        .map_err(|e| ApiError::Internal(format!("MB error for release {release_mbid}: {e}")))?;

    let cached = CachedAlbumTracks {
        release_mbid: release_mbid.clone(),
        tracks: mb_tracks
            .into_iter()
            .map(|t| CachedTrack {
                recording_mbid: t.recording_mbid,
                title: t.title,
            })
            .collect(),
    };

    // Cache with caller-specified TTL
    let json = serde_json::to_string(&cached).map_err(|e| ApiError::Internal(e.to_string()))?;
    let _ = queries::cache::set(
        state.db.conn(),
        &cache_key,
        "musicbrainz",
        &json,
        ttl_seconds,
    )
    .await;

    Ok(cached)
}

/// Given a release-group MBID, find the first release MBID.
async fn resolve_release_from_group(release_group_mbid: &str) -> Result<String, ApiError> {
    tokio::time::sleep(std::time::Duration::from_millis(1100)).await;

    let client = reqwest::Client::builder()
        .user_agent("Shanty/0.1.0 (shanty-music-app)")
        .build()
        .map_err(|e| ApiError::Internal(e.to_string()))?;

    let url = format!(
        "https://musicbrainz.org/ws/2/release?release-group={release_group_mbid}&fmt=json&limit=1"
    );

    let resp: serde_json::Value = client
        .get(&url)
        .send()
        .await
        .map_err(|e| ApiError::Internal(e.to_string()))?
        .json()
        .await
        .map_err(|e| ApiError::Internal(e.to_string()))?;

    resp.get("releases")
        .and_then(|r| r.as_array())
        .and_then(|arr| arr.first())
        .and_then(|r| r.get("id"))
        .and_then(|id| id.as_str())
        .map(String::from)
        .ok_or_else(|| ApiError::NotFound(format!("no releases for group {release_group_mbid}")))
}

#[derive(Deserialize)]
pub struct ArtistFullParams {
    #[serde(default)]
    quick: bool,
}

async fn get_artist_full(
    state: web::Data<AppState>,
    path: web::Path<String>,
    query: web::Query<ArtistFullParams>,
) -> Result<HttpResponse, ApiError> {
    let id_or_mbid = path.into_inner();
    let quick_mode = query.quick;
    let result = enrich_artist(&state, &id_or_mbid, quick_mode).await?;
    Ok(HttpResponse::Ok().json(result))
}

/// Enrich an artist's data: fetch release groups, track lists, compute totals.
/// Can be called from HTTP handlers or background tasks.
pub async fn enrich_artist(
    state: &AppState,
    id_or_mbid: &str,
    quick_mode: bool,
) -> Result<serde_json::Value, ApiError> {
    // Resolve artist: local ID or MBID
    let (artist, id, mbid) = if let Ok(local_id) = id_or_mbid.parse() {
        let artist = queries::artists::get_by_id(state.db.conn(), local_id).await?;
        let mbid = match &artist.musicbrainz_id {
            Some(m) => m.clone(),
            None => {
                let results = state
                    .search
                    .search_artist(&artist.name, 1)
                    .await
                    .map_err(|e| ApiError::Internal(e.to_string()))?;
                results.into_iter().next().map(|a| a.id).ok_or_else(|| {
                    ApiError::NotFound(format!("no MBID for artist '{}'", artist.name))
                })?
            }
        };
        (artist, Some(local_id), mbid)
    } else {
        let mbid = id_or_mbid.to_string();

        // Direct MBID lookup — first check local DB, then MusicBrainz
        let local = {
            // Check if any local artist has this MBID
            let all = queries::artists::list(state.db.conn(), 1000, 0).await?;
            all.into_iter()
                .find(|a| a.musicbrainz_id.as_deref() == Some(&mbid))
        };

        if let Some(a) = local {
            let local_id = a.id;
            (a, Some(local_id), mbid)
        } else {
            // Look up artist name from MusicBrainz by MBID — don't create a local record
            let (name, _disambiguation) = state
                .mb_client
                .get_artist_by_mbid(&mbid)
                .await
                .map_err(|e| ApiError::NotFound(format!("artist MBID {mbid} not found: {e}")))?;

            // Create a synthetic artist object for display only (not saved to DB)
            let synthetic = shanty_db::entities::artist::Model {
                id: 0,
                name,
                musicbrainz_id: Some(mbid.clone()),
                added_at: chrono::Utc::now().naive_utc(),
                top_songs: "[]".to_string(),
                similar_artists: "[]".to_string(),
            };
            (synthetic, None, mbid)
        }
    };

    // Fetch release groups and filter by allowed secondary types
    let all_release_groups = state
        .search
        .get_release_groups(&mbid)
        .await
        .map_err(|e| ApiError::Internal(e.to_string()))?;
    let allowed = state.config.read().await.allowed_secondary_types.clone();
    let release_groups: Vec<_> = all_release_groups
        .into_iter()
        .filter(|rg| {
            if rg.secondary_types.is_empty() {
                true // Pure studio releases always included
            } else {
                // Include if ALL of the release group's secondary types are in the allowed list
                rg.secondary_types.iter().all(|st| allowed.contains(st))
            }
        })
        .collect();

    // Get all wanted items for this artist
    let all_wanted = queries::wanted::list(state.db.conn(), None).await?;
    let artist_wanted: Vec<_> = all_wanted
        .iter()
        .filter(|w| id.is_some() && w.artist_id == id)
        .collect();

    // Build a set of wanted item recording MBIDs and their statuses for fast lookup (MBID only)
    let wanted_by_mbid: std::collections::HashMap<&str, &WantedStatus> = artist_wanted
        .iter()
        .filter_map(|w| w.musicbrainz_id.as_deref().map(|mbid| (mbid, &w.status)))
        .collect();

    // Get local albums
    let local_albums = if let Some(local_id) = id {
        queries::albums::get_by_artist(state.db.conn(), local_id).await?
    } else {
        vec![]
    };

    // Quick mode: if no wanted items and ?quick=true, skip per-album MB fetches
    let skip_track_fetch = quick_mode && artist_wanted.is_empty();

    // Build full album info — fetch tracklists (from cache or MB) for each release group
    // Deduplicate at the artist level:
    // - available: unique recording MBIDs across all releases
    // - watched/owned: unique wanted item MBIDs (so the same wanted item matching
    //   multiple recordings across releases only counts once)
    let mut seen_available: std::collections::HashSet<String> = std::collections::HashSet::new();
    let mut seen_watched: std::collections::HashSet<String> = std::collections::HashSet::new();
    let mut seen_owned: std::collections::HashSet<String> = std::collections::HashSet::new();
    let mut albums: Vec<FullAlbumInfo> = Vec::new();

    for rg in &release_groups {
        if skip_track_fetch {
            // Fast path: just list the release groups without track counts
            albums.push(FullAlbumInfo {
                mbid: rg.first_release_id.clone().unwrap_or_else(|| rg.id.clone()),
                title: rg.title.clone(),
                release_type: rg.primary_type.clone(),
                date: rg.first_release_date.clone(),
                track_count: 0,
                local_album_id: None,
                watched_tracks: 0,
                owned_tracks: 0,
                downloaded_tracks: 0,
                total_local_tracks: 0,
                status: "unwatched".to_string(),
            });
            continue;
        }

        // If artist has any watched items, cache permanently (10 years);
        // otherwise cache for 7 days (just browsing)
        let is_watched = !artist_wanted.is_empty();
        let cache_ttl = if is_watched {
            10 * 365 * 86400
        } else {
            7 * 86400
        };

        let cached = match get_cached_album_tracks(
            state,
            &rg.id,
            rg.first_release_id.as_deref(),
            cache_ttl,
            is_watched,
        )
        .await
        {
            Ok(c) => c,
            Err(e) => {
                tracing::warn!(rg_id = %rg.id, title = %rg.title, error = %e, "failed to fetch tracks");
                // Still show the album, just without track data
                albums.push(FullAlbumInfo {
                    mbid: rg.first_release_id.clone().unwrap_or_else(|| rg.id.clone()),
                    title: rg.title.clone(),
                    release_type: rg.primary_type.clone(),
                    date: rg.first_release_date.clone(),
                    track_count: 0,
                    local_album_id: None,
                    watched_tracks: 0,
                    owned_tracks: 0,
                    downloaded_tracks: 0,
                    total_local_tracks: 0,
                    status: "unwatched".to_string(),
                });
                continue;
            }
        };

        let track_count = cached.tracks.len() as u32;

        // Match each track against wanted items by recording MBID or title
        let mut watched: u32 = 0;
        let mut owned: u32 = 0;
        let mut downloaded: u32 = 0;

        for track in &cached.tracks {
            let rec_id = &track.recording_mbid;

            // Add to artist-level unique available set
            seen_available.insert(rec_id.clone());

            // Match by recording MBID only
            if let Some(s) = wanted_by_mbid.get(rec_id.as_str()) {
                watched += 1;
                seen_watched.insert(rec_id.clone());
                match s {
                    WantedStatus::Owned => {
                        owned += 1;
                        seen_owned.insert(rec_id.clone());
                    }
                    WantedStatus::Downloaded => {
                        downloaded += 1;
                    }
                    _ => {}
                }
            }
        }

        // Local album match
        let local = local_albums
            .iter()
            .find(|a| a.name.to_lowercase() == rg.title.to_lowercase());
        let local_album_id = local.map(|a| a.id);
        let local_tracks = if let Some(aid) = local_album_id {
            queries::tracks::get_by_album(state.db.conn(), aid)
                .await
                .unwrap_or_default()
                .len() as u32
        } else {
            0
        };

        let status = if owned > 0 && owned >= track_count && track_count > 0 {
            "owned"
        } else if owned > 0 || downloaded > 0 {
            "partial"
        } else if watched > 0 {
            "wanted"
        } else {
            "unwatched"
        };

        albums.push(FullAlbumInfo {
            mbid: cached.release_mbid.clone(),
            title: rg.title.clone(),
            release_type: rg.primary_type.clone(),
            date: rg.first_release_date.clone(),
            track_count,
            local_album_id,
            watched_tracks: watched,
            owned_tracks: owned,
            downloaded_tracks: downloaded,
            total_local_tracks: local_tracks,
            status: status.to_string(),
        });
    }

    // Sort: owned first, then partial, then wanted, then unwatched; within each by date
    albums.sort_by(|a, b| {
        let order = |s: &str| match s {
            "owned" => 0,
            "partial" => 1,
            "wanted" => 2,
            _ => 3,
        };
        order(&a.status)
            .cmp(&order(&b.status))
            .then_with(|| a.date.cmp(&b.date))
    });

    // Deduplicated artist-level totals
    let total_available_tracks = seen_available.len() as u32;
    let total_artist_watched = seen_watched.len() as u32;
    let total_artist_owned = seen_owned.len() as u32;

    let artist_status = if total_artist_owned > 0
        && total_artist_owned >= total_available_tracks
        && total_available_tracks > 0
    {
        "owned"
    } else if total_artist_watched > 0 {
        "partial"
    } else {
        "unwatched"
    };

    // Cache artist-level totals for the library listing page
    if !skip_track_fetch && let Some(local_id) = id {
        let cache_key = format!("artist_totals:{local_id}");
        let totals = serde_json::json!([
            total_available_tracks,
            total_artist_watched,
            total_artist_owned
        ]);
        let _ = queries::cache::set(
            state.db.conn(),
            &cache_key,
            "computed",
            &totals.to_string(),
            if artist_wanted.is_empty() {
                7 * 86400
            } else {
                10 * 365 * 86400
            },
        )
        .await;
    }

    Ok(serde_json::json!({
        "artist": artist,
        "albums": albums,
        "artist_status": artist_status,
        "total_available_tracks": total_available_tracks,
        "total_watched_tracks": total_artist_watched,
        "total_owned_tracks": total_artist_owned,
        "enriched": !skip_track_fetch,
    }))
}

/// Enrich all watched artists in the background, updating their cached totals.
pub async fn enrich_all_watched_artists(state: &AppState) -> Result<u32, ApiError> {
    let all_wanted = queries::wanted::list(state.db.conn(), None).await?;

    // Collect unique artist IDs that have any wanted items
    let mut artist_ids: Vec<i32> = all_wanted.iter().filter_map(|w| w.artist_id).collect();
    artist_ids.sort();
    artist_ids.dedup();

    let mut count = 0u32;
    for artist_id in &artist_ids {
        match enrich_artist(state, &artist_id.to_string(), false).await {
            Ok(_) => count += 1,
            Err(e) => tracing::warn!(artist_id = artist_id, error = %e, "failed to enrich artist"),
        }
    }

    Ok(count)
}

async fn add_artist(
    state: web::Data<AppState>,
    body: web::Json<AddArtistRequest>,
) -> Result<HttpResponse, ApiError> {
    if body.name.is_none() && body.mbid.is_none() {
        return Err(ApiError::BadRequest("provide name or mbid".into()));
    }
    let summary = shanty_watch::add_artist(
        state.db.conn(),
        body.name.as_deref(),
        body.mbid.as_deref(),
        &state.mb_client,
    )
    .await?;

    // Enrich the newly watched artist in the background so library totals are populated
    if let Some(ref mbid) = body.mbid {
        let state = state.clone();
        let mbid = mbid.clone();
        tokio::spawn(async move {
            let _ = enrich_artist(&state, &mbid, false).await;
        });
    }

    Ok(HttpResponse::Ok().json(serde_json::json!({
        "tracks_added": summary.tracks_added,
        "tracks_already_owned": summary.tracks_already_owned,
        "errors": summary.errors,
    })))
}

async fn delete_artist(
    state: web::Data<AppState>,
    path: web::Path<i32>,
) -> Result<HttpResponse, ApiError> {
    let id = path.into_inner();
    queries::artists::delete(state.db.conn(), id).await?;
    Ok(HttpResponse::NoContent().finish())
}